The present invention relates generally to methods and apparatus for cooling patients for therapeutic purposes, and more particularly to systems for establishing central venous access while providing a means for cooling a patient.
It has been discovered that the medical outcome for a patient suffering from severe brain trauma or from ischemia caused by stroke or heart attack is degraded if the patient""s body temperature rises above normal (38xc2x0 C.). It is further believed that the medical outcome for many such patients might be significantly improved if the patients were to be cooled relatively quickly for a short period, e.g., 24-72 hours. Apart from the therapeutic benefits of hypothermia, the outcomes for brain trauma or ischemia patients that develop fevers is worse than for patients that do not develop fevers. Consequently, temperature management for such patients is important, even when hypothermia is not to be used to treat the patients. Moreover, prophylactic short-term hypothermia might help patients undergoing minimally invasive heart surgery and aneurysm surgery.
The affected organ, in any case, is the brain. Accordingly, systems and methods have been disclosed that propose cooling blood flowing to the brain through the carotid artery. An example of such systems and methods is disclosed in co-pending U.S. patent application Ser. No. 09/063,984, filed Apr. 21, 1998, owned by the present assignee and incorporated herein by reference. In the referenced application, various catheters are disclosed which can be advanced into a patient""s carotid artery and through which coolant can be pumped in a closed circuit, to remove heat from the blood in the carotid artery and thereby cool the brain. The referenced devices have the advantage over other methods of cooling (e.g., wrapping patients in cold blankets) of being controllable, relatively easy to use, and of being capable of rapidly cooling and maintaining blood temperature at a desired set point.
As recognized in co-pending U.S. patent application Ser. No. 09/133,813, filed Aug. 13, 1998, owned by the present assignee and incorporated herein by reference, the abovementioned advantages in treating brain trauma/ischemic patients by cooling can also be realized by cooling the patient""s entire body, i.e., by inducing systemic hypothermia. The advantage of systemic hypothermia is that, as recognized by the present assignee, to induce systemic hypothermia a cooling catheter or other cooling device need not be advanced into the blood supply of the brain, but rather can be easily and quickly placed into the relatively large vena cava of the central venous system.
Moreover, since many patients already are intubated with central venous catheters for other clinically approved purposes anyway, providing a central venous catheter that can also cool the blood, if only to manage temperature and thereby ameliorate fever spikes, requires no additional surgical procedures for those patients. A cooling central venous catheter is disclosed in the present assignee""s co-pending U.S. patent application Ser. No. 09/253,109, filed Feb. 19, 1999 and incorporated herein by reference. The present invention is directed to such a device.
A heat exchange catheter, preferably made of urethane, includes a catheter body defining at least a coolant supply lumen and a coolant return lumen. First and second heat exchange membranes are disposed along a distal portion of the catheter body, and the heat exchange membranes communicate with one or more of the lumens. With this structure, coolant can be supplied to the heat exchange membranes via the coolant supply lumen and received from the heat exchange membranes via the coolant return lumen to effect a closed loop heat exchanger for cooling and/or warming a patient.
Preferably, the first and second heat exchange membranes define first and second interiors respectively communicating with first and second coolant supply ports in the coolant supply lumen. Also, first and second coolant return ports are formed in the coolant return lumen, and coolant flows from the heat exchange membranes through the return ports. At least one anchor can be engaged with the catheter body to fasten the catheter to a patient.
In addition to the coolant supply and return lumens, the catheter can define a drug delivery lumen and a guide wire lumen. A connector manifold can be engaged with the catheter body to interconnect the lumens with respective connector lines. More specifically, the connector manifold defines plural channels, and each channel establishes a respective pathway for fluid communication between a respective connector line and a respective lumen. As set forth in detail below, the anchor is on the connector manifold.
To provide for infusing medicament into a patient while simultaneously cooling the patient, at least one drug delivery port is formed in the catheter body. Preferably, the drug delivery port is formed at a location that is between two adjacent heat exchange membranes to establish a pathway for fluid communication from the drug delivery lumen to a location outside the catheter body. If desired, additional drug delivery ports can be formed along the length of the catheter.
In another aspect, a method for making a heat exchange catheter includes disposing a multi-lumen catheter body in a connector manifold mold, and disposing plural connector tubes in the connector manifold mold. Also, the method includes interconnecting a respective lumen with a respective connector tube using a mandrel, and then directing a plastic material into the connector manifold mold. The mandrels are then removed, such that a respective channel is defined between each respective lumen and its connector line.
In another aspect, a method is disclosed for treating a patient. The method includes advancing a heat exchange catheter device into the patient, and then circulating coolant through the catheter device while preventing infusion of the coolant directly into the patient""s bloodstream. Per the present invention, the catheter device includes a heat exchange region that is established by: one or more heat exchange membranes, or one or more hollow fibers, or one or more chamber-defining enclosures.
In still another aspect, a catheter configured as a Swan-Ganz catheter or central venous catheter has at least one balloon-like membrane distally located on the catheter for heating or cooling blood in a patient. More particularly, the membrane defines an interior communicating with a coolant supply lumen of the catheter and with a coolant return lumen of the catheter, to circulate coolant through the interior of the membrane.